Replacement of articulating joints in humans has become increasingly common. In the replacement of many articulating joints, it is necessary to implant a prosthesis within a long bone, the prosthesis completely replacing the articulating end of the bone. For example, a distal femoral element is often necessary when replacing a knee joint; a proximal femoral element for a hip joint; a proximal humeral element for a shoulder joint; etc.
Recently, modular prosthesis components for replacing the end of a long bone in joint replacement surgery have become more popular. Successful joint replacement surgery depends, in part, on careful selection of prosthesis components to replace portions of the patient's bone with components that properly fit with existing bone and restore natural function to the joint being replaced. In order to provide prostheses that would exactly fit each patient who might require joint replacement surgery, hospitals would have to inventory an extraordinary number of single piece prostheses. With single piece prostheses, the only other option is to stock fewer prostheses with the result that many patients will receive a prosthesis that fits well only in one aspect.
As an alternative, modular prosthesis components have been developed, such as the modular sleeve prosthesis of U.S. Pat. No. 4,790,852, or the modular stem, sleeve and neck combinations disclosed in U.S. Pat. Nos. 5,002,578 and 5,725,592. While improving the situation described above in some respects, existing modular prosthesis configurations may still be improved. For example, present designs do not allow for a single modular sleeve to engage a wide variety of stem sizes, requiring multiple sleeves of the same size for various different stem size combinations and increasing rather than decreasing inventory. Present modular sleeve designs do not allow for sleeves of varying lengths to be used modularly with existing stems while still providing a desired snug fit between prosthesis components. Extended length sleeves are particularly desirable when the joint replacement surgery is necessary due to cancer or some other degenerative bone disease or condition and greater filling of the long bone in proximity to the joint is desired. In addition, present designs do not provide all of these modularity advantages while providing for assembly of all the modular components within the patient--allowing the surgeon to align and properly fit each modular component separately and reducing the chances of malaligning or misfitting a component.